How much space does Blender take up on a computer?
Taken from https://www.blender.org/download/requirements/

Blender 2.66a - Needs about 186Mb of harddrive space
Blender 2.78b - Needs about 330Mb of harddrive space
Blender 2.83&lt; - Needs about 395Mb of harddrive space

Minimum (basic usage) hardware
32-bit dual core 2Ghz
CPU with SSE2 support.
2 GB RAM Physical Ram
24 bits 1280×768 display
Mouse or trackpad
OpenGL 2.1 compatible graphics with 512 MB RAM  

Recommended hardware
64-bit quad core CPU
8 GB RAM Physical Ram
Full HD display with 24 bit color
Three button mouse
OpenGL 3.2 compatible graphics with 2 GB RAM  

Optimal (production-grade) hardware
64-bit eight core CPU
16 GB RAM Physical Ram
Two full HD displays with 24 bit color
Three button mouse and graphics tablet
Dual OpenGL 3.2 compatible graphics cards with 4 GB RAM 

For Your reference My Production system Built...
Windows 10 64bit
Asus COG8580 i73770K 3.5GHz 4 Core 8 Logical Processor
16GB Ram Physical Ram
2 X Eizo Screens
Basic 3 button wired Logitech mouse
Nvidia GTX970 + Nvidia GTX680 (Dual Graphics)
2 X Solid state drives 260GB + 120GB
1 X SATA 1TB drive 

For learning purposes blender should run just fine with any system that isn't too old to begin with. If you are having problem I do suggest installing an earlier build since those versions are less intensive and a learning tool before investing on a more appropriate system.